The present invention relates generally to the manufacture of mattresses.
Mattresses are well-known in the art and are commonly used alone or in combination with additional components to form a bed on which a person may rest and/or sleep. Many types of conventional mattresses comprise a spring unit to provide its user with a satisfactory level of support and comfort.
A mattress spring unit typically includes an upper frame and a lower frame which are spaced slightly apart and which are arranged in a substantially parallel configuration. Each frame (also commonly referred to as a wire box) includes a rigid and durable wire, or rod, which is formed into a substantially rectangular design, said wire defining the outer periphery of its associated frame. In addition, a mattress spring unit typically comprises a plurality of uniformly spaced apart metal springs, or coils, which extend between the upper and lower frames. Each spring includes a longitudinal axis which extends substantially at a right angle relative to the upper and lower frames. As can be appreciated, the plurality of springs enables the upper frame to move, or give, towards the lower frame when a downward force is applied onto the upper frame. As a result, when an individual rests on the upper frame of the spring unit, the body weight of said individual is uniformly absorbed by the plurality of springs, which is highly desirable.
A layer of cushioning material, in the form of a pad, is typically secured onto each frame of a mattress spring unit. The layer of cushioning material is commonly in the form of a non-woven fabric having an approximate thickness of ¾ of an inch. One type of cushioning material which is commonly secured onto the upper and lower frames of a mattress spring unit is a Flexatron® cushioning pad which is manufactured by Kingsdown, Inc.
The layer of cushioning material is typically secured onto each frame of the mattress spring unit in the following manner. Specifically, the layer of cushioning material is disposed against the outer surface of each frame. The outer periphery of each layer of material is pulled tightly past the wire of its associated frame. A short length of said layer is then wrapped around the wire and is disposed against the underside of a portion of said layer, thereby creating a double thickness portion of said layer of material with said wire trapped therebetween. With said layer of cushioning material double-backed in the manner described above, a conventional, pneumatically-driven staple gun is used to secure together the double-backed portion of said layer of material, thereby trapping the wire therewithin.
Typically, metallic C-shaped staples, or rings, are used to secure together the double-backed portion of said layer of material at approximately 2 inch intervals. Specifically, the staple gun dispenses each C-shaped staple through the double-backed portion of said layer of material and bends the sharpened free ends of each C-shaped staple into direct alignment and contact with one another.
With a layer of cushioning material secured onto each wire box of a mattress spring unit, many high-end mattresses often dispose 2, 3 or 4 layers of varying density foam rubber on top of the spring unit. As can be appreciated, these layers of foam rubber serve to significantly increase the level of comfort of the mattress, which is highly desirable. Having disposed multiple layers of foam rubber onto the mattress spring unit, an outer layer of fabric (e.g., a quilted cotton material) is sewn over the spring unit and the layers of foam to form the finished mattress.
It should be noted that conventional high-end mattress manufacturing techniques secure together particular layers of the mattress (and, in particular, the multiple layers of foam rubber) using an adhesive prior to sewing the outer layer of quilted cotton material around the remainder of the mattress. Specifically, one or both of the contact surfaces of adjacent layers are sprayed with an adhesive. With the adhesive sprayed onto one or both of the contact surfaces of adjacent layers, the layers are first aligned and then drawn into contact with one another.
It should be noted that the aforementioned method of using adhesives to secure together multiple layers of a mattress suffers from a few notable drawbacks.
As a first drawback, the use of adhesives to secure together multiple layers of a mattress results in a significant level of waste. Specifically, if the layers of material are secured together in misalignment, there is no means to separate the layers and attempt to re-secure the layers. As a result, layers of material which are secured together in misalignment are often discarded as waste, thereby increasing manufacturing costs, which is highly undesirable.
As a second drawback, the use of adhesives to secure together multiple layers of a mattress creates an unhealthy amount of fumes where the mattress is manufactured, thereby creating a potentially hazardous working environment, which is highly undesirable.
As a third drawback, the use of adhesives to secure together multiple layers of a mattress often creates audible crackling sounds as the adhesives age, which is highly undesirable.